The present invention relates to a method for producing a photoelectric conversion device comprising a semiconductor fine particle sensitized by a dye, a photoelectric conversion device produced by the method and a photoelectric cell comprising the photoelectric conversion device.
Photoelectric conversion devices have been used for optical sensors, copying machines, photovoltaics, etc. Such photoelectric conversion devices that use a metal, a semiconductor, an organic pigment, a dye, a combination thereof, etc. have been made practicable.
Photoelectric conversion devices using a semiconductor fine particle sensitized by a dye, hereinafter referred to as xe2x80x9cdye-sensitized photoelectric conversion device,xe2x80x9d and materials and producing methods therefor have been disclosed in U.S. Pat. Nos. 4,927,721, 4,684,537, 5,084,365, 5,350,644, 5,463,057, 5,525,440, WO 98/50393, Japanese Patent Laid-Open No. 7-249790 and Japanese Patent Publication No. 10-504521. The dye-sensitized photoelectric conversion devices can be produced at reduced costs because an inexpensive metal oxide semiconductor such as titanium dioxide can be used therefor without purification to a high purity. However, the conventional, dye-sensitized photoelectric conversion devices do not necessarily have sufficiently high photoelectric conversion efficiency. It is thus highly desired to develop a dye-sensitized photoelectric conversion device exhibiting improved photoelectric conversion efficiency.
An object of the present invention is to provide a method for producing a dye-sensitized photoelectric conversion device excellent in photoelectric conversion efficiency, a photoelectric conversion device produced thereby and a photoelectric cell comprising the device.
As a result of intense research in view of the above object, the inventor has found that a dye-sensitized photoelectric conversion device using a semiconductor fine particle treated with a particular compound is excellent in photoelectric conversion efficiency. The present invention has been accomplished by the finding.
Thus, a method of the present invention is a method for producing a photoelectric conversion device comprising a conductive support and a photosensitive layer containing a semiconductor fine particle on which a dye is adsorbed, wherein the semiconductor fine particle is treated with a compound represented by the following general formula (I): 
In the general formula (a), X represents an oxygen atom, a sulfur atom, a selenium atom or NY, in which Y represents a hydrogen atom, an aliphatic hydrocarbon group, a hydroxyl group or an alkoxy group; R1, R2, R3 and R4 independently represent a hydrogen atom, an aliphatic hydrocarbon group, an aryl group, a heterocyclic group, xe2x80x94N(R5)(R6), xe2x80x94C(xe2x95x90O)R7, xe2x80x94C(xe2x95x90S)R8, xe2x80x94SO2R9 or xe2x80x94OR10; R5 and R6 independently have the same meaning as R1, R2, R3 and R4; R7, R8 and R9 independently represent a hydrogen atom an aliphatic hydrocarbon group, an aryl group, a heterocyclic group, xe2x80x94N(R5)(R6), xe2x80x94OR10 or xe2x80x94SR11; and R10 and R11 independently represent a hydrogen atom or an aliphatic hydrocarbon group.
In the method for producing a photoelectric conversion device of the present invention, it is preferred that the semiconductor fine particle is treated with a solution comprising the compound represented by the general formula (I). The semiconductor fine particle is preferably treated with the compound represented by the general formula (I) after or while the dye is adsorbed on the semiconductor fine particle.
In the general formula (I), X is preferably an oxygen atom. The compound represented by the general formula (I) preferably has xe2x80x94Si(R12)(R13)(R14), in which R12, R13 and R14 independently represent a hydroxyl group, an alkoxy group, a halogen atom, an isocyanate group or an aliphatic hydrocarbon group, at least one of R12, R13 and R14 being an alkoxy group, a halogen atom or an isocyanate group.
In the method for producing a photoelectric conversion device of the present invention, it is preferable that the semiconductor fine particle is treated with the compound represented by the general formula (I) and a compound represented by the following general formula (II):
Mp.Zqxe2x80x83xe2x80x83(II) 
wherein M represents an alkaline metal ion, an alkaline earth metal ion, an ammonium ion, an imidazolium ion or a pyridinium ion; Z represents a halide ion, a carboxylate ion, a sulfonate ion, a phosphonate ion, a bis-sulfonylimide ion, a tris-sulfonylmethide ion, a sulfate ion, a thiocyanate ion, a cyanate ion, a perchlorate ion, a tetrafluoroborate ion or a hexafluorophosphate ion; and p and q independently represent an integer of 1 or more. In the general formula (II), Z is particularly preferably an iodide ion.
If the semiconductor fine particle is treated with the compound represented by the general formula (I) and the compound represented by the general formula (II), the semiconductor fine particle is preferably treated with a solution comprising the compound represented by the general formula (I) and a solution comprising the compound represented by the general formula (II), or with a solution comprising the compound represented by the general formula (I) and the compound represented by the general formula (II). It is particularly preferred that the semiconductor fine particle is treated with the compound represented by the general formula (I) while the dye is adsorbed on the semiconductor fine particle, and the semiconductor fine particle is then treated with the compound represented by the general formula (II). In this case, M in the general formula (II) is particularly preferably a quaternary ammonium ion. Further, it is also particularly preferred that the semiconductor fine particle is treated with the compound represented by the general formula (II) while the dye is adsorbed on the semiconductor fine particle, and the semiconductor fine particle is then treated with the compound represented by the general formula (I). In this case, M in the general formula (II) is particularly preferably a lithium ion.
In the case where the semiconductor fine particle is treated with the compound represented by the general formula (I) after the dye is adsorbed thereon, the semiconductor fine particle is particularly preferably treated with a compound having a basic group while the semiconductor fine particle is treated with the compound represented by the general formula (I). The compound having a basic group is preferably pyridine or a derivative thereof. Further, the dye used in the present invention is preferably a ruthenium complex dye.
A photoelectric conversion device of the present invention is obtainable by the above-mentioned method of the present invention. A photoelectric cell of the present invention comprises the photoelectric conversion device.